Rate of and risk factors for acute inpatient mortality after orthopaedic surgery

Background: Orthopaedic surgeons operate on a diverse group of patients, and many of these patients have concomitant medical problems. The purpose of this study was to identify the rate of mortality and to evaluate the risk factors associated with mortality after orthopaedic surgery. Methods: Data from the National Hospital Discharge Survey, a nationwide sample of hospital admissions, were obtained for the years 1995 through 1997. The study was limited to hospital admissions. Univariate and multivariate analyses were performed. Results: The 43,215 inpatient orthopaedic operations that we evaluated were associated with a mortality rate of 0.92%. Seventy-seven percent of all deaths occurred after procedures performed for patients who were more than seventy years old, and 50% of all deaths occurred after operations performed for the treatment of hip fractures. The independent preoperative medical risk factors for death included chronic renal failure, congestive heart failure, metastasis to bone, atrial fibrillation, chronic obstructive pulmonary disease, and osteomyelitis. The risk factors of diabetes, coronary artery disease, peripheral vascular disease, septic arthritis, and rheumatoid arthritis did not achieve significance. Among orthopaedic subspecialty categories, operations for tumors, trauma, and infection were associated with elevated mortality rates. In a predictive model, five critical risk factors were identified as most helpful in identifying patients at risk for death: chronic renal failure, congestive heart failure, chronic obstructive pulmonary disease, hip fracture, and an age of greater than seventy years. The mortality rate was 0.25% for patients with no critical risk factors. A linear increase in mortality was seen with increasing numbers of critical risk factors (p < 0.005). Conclusion: Death is rare after orthopaedic operations. In the United States, the rate of acute mortality after inpatient orthopaedic surgical procedures is approximately 1% for all patients, 3.1% for patients with a hip fracture, and 0.5% for patients without a hip fracture. These data will aid orthopaedic surgeons in predicting operative mortality for their patients.